// 创建一个固定长度的随机值
export const createUid = (len?: number): string => {
  const temp_url = URL.createObjectURL(new Blob())
  const uuid = temp_url.toString()
  URL.revokeObjectURL(temp_url)
  const ll = uuid.substring(uuid.lastIndexOf('/') + 1)
  return len ? ll.substring(ll.length - len) : ll
}
